Siding Calculator

Siding is an area first and a panel count second. Measure the perimeter and the height, take off doors and windows, and add waste for cuts. Panels stay at 0 until you type the coverage of one panel, because lap siding and panel siding do not share a cover width. A gable is a triangle on top of this rectangle. Add it, or leave it out and say so.

Siding is an exterior wall area with openings removed, then a panel yield you supply. A 20 m perimeter at 3 m is 60 square metres. One door and two windows remove 1.9 and 2.4, leaving 55.7. If each panel covers 1 square metre, you need 56 panels before waste, because 55.7 rounds up. Ten percent waste is about 61.3 square metres and 62 panels. The coverage field starts at 0 so that 56 never appears until you type a real panel. A lap board's cover width is the exposed face. A 150 mm board that covers 130 mm is 0.13 m of cover. The square metres of one length are the cover width times the length. Type that product, not the stock width.

Gables, dormer cheeks, and returns are extra. A triangular gable is half the base times the rise. Add it to your own area, then divide, or raise waste and know you guessed. A garage door of 5 square metres left as a 1.9 square metre house door overstates the siding. Set doors to 0 and subtract the real opening from the gross area before you rely on the net line, or accept the error and measure. Corners, starter strips, and J-channel are linear trims. This page does not count them. Measure the outside corners and the opening perimeters for those.

Exterior paint uses the same opening allowances so you can compare a paint area and a siding area. They are not interchangeable orders. Render uses the same openings and a bag coverage that also starts at 0. Drywall is the inside. Cinder block is the structure, not the cladding. None of those counts should be added to the panel count.

There is no price per panel and no labor rate. Waste is the only softness in the formula, and it is visible. If you are siding one elevation, do not enter the whole house perimeter. Measure that face.

Wall perimeter starts at 120 ft. Wall perimeter in feet. Switch to m / cm for metres. Wall height starts at 9 ft. Wall height in feet. Switch to m / cm for metres. Doors starts at 1. Each door removes 20 sq ft (1.9 m²). A garage door is larger. Measure it and do not leave it as one house door. Windows starts at 2. Each window removes 13 sq ft (1.2 m²). Waste allowance starts at 10 %. Cuts at openings and corners. Staggered laps may need more. Coverage per panel starts at 7 sq ft. 7 sq ft is a typical 12 ft plank at a 7 in exposure (exposure × length). Replace it with the coverage printed for the panel you buy.

Cover width is the number that makes lap siding come out right. A board 150 mm wide that laps 20 mm covers 130 mm. A 3.6 m length of that board covers 0.13 times 3.6, which is 0.468 square metres. Type 0.468, not 0.54. On the 55.7 square metre example, 0.468 square feet per board is 119 boards before waste. A panel’s cover area is what you type, in square feet. The form starts from a typical plank, not from a guessed sheet. Vertical board-and-batten is the cover width of the board plus the batten if the batten is a separate piece you buy. Count the battens as a linear extra: the wall height times the number of seams. This page will not do that second count. Gable area is base times rise divided by two. A 6 m gable that rises 2 m is 6 square metres. Add it to the net wall before you divide, or run the numbers beside the page. Inside corners, outside corners, and window trim are linear. Measure them with a tape after the area is settled. There is still no price per panel.